Cable type operating mechanism for an electric circuit breaker



Oct. 22, 1957 11R. coast-:SHALL 2,810,808

CABLE TYPE OPERATING MECEANISM FCE AN ELECTRIC CIRCUIT BREAKER FiledJan. 25, 1955 v3 ya b ma M Hmorneg.

United States Patent O CABLE TYPE OPERATING MECHANISM FOR AN ELECTRICCIRCUIT BREAKER Thellwell R. Coggeshall, Cynwyd, Pa., assigner toGeneral Electric Company, a corporation of New York Application January25, 1955, Serial No. 483,945

14 Claims. (Cl. Zim-161) This invention relates to an operatingmechanism for transmitting circuit-controlling movement between a sourceof motive power and the movable switch members of a circuit breaker.

Where it is necessary to transmit such circuit-controlling movement overa relatively great distance, it has been customary to utilize anoperating mechanism which consists of a series of interconnected,substantially rigid links and levers. Because of the precise motionrequirements frequently involved, it has been necessary to resort tocomplex mechanisms which utilize a large number of such rigid links andlevers. As an example, reference may be had to the straight-linemechanism disclosed in Rankin Patent No. 1,754,179, assigned to theassignee of the present invention. Frequently too, each of the links andlevers of such mechanisms must be relatively massive in construction inorder to withstand the high forces involved. As a result, the compositemechanism has a high effective mass which tends to retard rapidacceleration of the switch parts. Frequently, as in the case of extremehigh speed breakers, such retardation is a serious disadvantage.

Accordingly, a primary object of my invention is to provide a circuitbreaker operating mechanism which is capable of providingprecisely-controlled movement of the breaker parts and yet has anexceptionally low ef- `fective mass.

Another disadvantage which is inherent in the conventional type ofcircuit breaker operating mechanism is that because of the large numberof links and levers, there is also a large number of interconnectingjoints. These joints invariably have an appreciable amount of play anddeflection which must be taken up before motion of all of the parts canbe initiated. Obviously, if such play and deilection is held to aminimum, the time required to initiate operation of the circuit breakermay be materially shortened.

Accordingly, another object of my invention is to construct a circuitbreaker operating mechanism in such a manner that an exceptionally lownumber of interconnecting joints is required, as a result of which playand deflection is held to a minimum.

In accordance with one form of my invention, a movable circuit breakerswitch member is interconnected to a source of motive power by means ofa low-mass operating mechanism which includes a flexible tension member,e. g., a steel cable, stationarily anchored at one end and connected atits other end to the switch member. A rotatable pulley is arranged toengage the tension member and is bodily movable to transmit circuitcontrolling movement to said switch member through said tension member.This pulley is coupled to the source of motive power by a linkage whichis actuable by the motive power source to bodily move the pulley wherebyto eiect circuit-controlling movement of said switch member.

My invention is especially applicable to multi-pole circuit breakerswherein a plurality of simultaneously-,operable switch members are to beoperated from a com- Cil mon source of motive power. For suchapplications, I provide a plurality of tension members each of which isstationarily anchored at one end and at its other end is connected to adifferent one of said switch members. A plurality of coaxially-mountedrotatable pulley structures are arranged to engage the tension membersand are bodilymovable in unison to transmit simultaneouscircuit-controlling movement to the switch members through said tensionmembers.

A practical problem involved in utilizing a cable-type operatingmechanism of the above type is that there is a tendency for the cable towhip during periods of abrupt mechanism deceleration. This imposes anundue strain on certain of the parts and, if excessive, can also causethe cable to become disengaged from its pulley or pulleys.

Accordingly, another object of my invention is to minimize thepossibility that whip will develop in the cable during operation of themechanism.

Other objects and advantages will appear more clearly from the followingdescription of an embodiment of my invention when taken in connectionwith the accompanying drawing wherein:

Fig. 1 shows a single pole circuit breaker having an operating mechanismconstructed in accordance with my invention; Fig. 2 is a reduced scalecross-sectional View taken along the line 2-2 of Fig. l; Fig. 3 is aplan view showing my invention applied to a multi-pole breaker; Fig. 4is a side elevational view of the multi-pole breaker of Fig. 3; whereasFig. 5 is an enlarged perspective view of a portion of the mechanism ofFigs. 3 and 4.

Referring more particularly to Figs. 1 and 2, l have shown a highvoltage oil circuit breaker comprising a single pole unit 7. This poleunit '7 comprises an oilfilled metallic tank 8, a pair of spaced-aparthigh voltage bushings 9 extending through the top of the tank, and apair of spaced-apart interrupting devices 10 mounted at the lower endsof the bushings. These interrupting devices 10, which may be of anyconventional form, such as, for example, shown in Coggeshall Patent No2,522,994, are electrically interconnected by means of a conventionalcontact blade 13 which is vertically reciprocable to eilect opening andclosing or" the circuit through the pole unit.

The solid lines of Fig. l show the Contact bla-:le 13 in its upper orclosed-circuit position wherein it is suitably latched by means whichwill soon be described. The contact blade 13 is biased toward its opencircuit position by means including a long-travel compression spring 14acting through an insulated lift rod 1S which is suitably secured to thecontact blade 13. The lift rod is guided for straight line motion bysuitable slide bearing structure such as 16 mounted within avertically-extending Vstationary sleeve 18. The compression openingspring 14, which is shown mounted within this sleeve 18, bears at itsupper end against a suitable fixed abutment and at its lower end againsta suitable shoulder member 17 secured to the movable lift rod 1S. Thus,when the contact blade 13 is unlatched, as during circuit breakertripping, it is driven rapidly downward toward its dottedline positionto effect opening of the circuit through the breaker. Initial downwardmovement is accelerated by the usual short-travel contact-openingsprings such as 19 within the interrupting devices 10. as seen in Fig.2.

For lifting the contact blade 13 to close the breaker, I provide asource of motive power such as a fluid motor 20. This iluid motorcomprises a cylinder 26, which is stationarily mounted on the tank 8 anda piston 27 which is vertically reciprocable within the cylinder 26.With the circuit breaker in open position, the piston 27 occupies adotted-line position at the upper end of the cylinder 26. Closing of thebreaker is effected by driving tne piston 27 downwardly into its loweror closed-circuit position, where it is shown by solid lines in Fig. l.This driving action is produced by supplying pressurized fluid to theupper side of the piston through a suitable electromagnetically-operatedclosing control valve at 28. Preferably, the valve 28 is of the typewhich, upon energization, opens to permit pressurized fluid to flowtherethrough and into cylinder 26, and upon deenergization, closes andvents the cylinder to atmosphere. The piston 27 is releasably held inits lower or closed-circuit position by means of a trippable hold-closedlatch 29 cooperating with a suitable latch roller 29h. For tripping thelatch 29, there is provided a suitable electromagnetic trip device 29awhich may be arranged in a well known manner to operate in response toany desired condition.

For transmitting the downward or circuit-closing movement of piston 27to the movable switch member 13, I provide a novel operating mechanismcomprising a flexible tension member, such as a multi-strand cable 30,which is stationarily anchored at one of its ends X and is fixed to theswitch member 13 at its other end Y. Preferably, such cable should be ofthe prestressed type thereby insuring that no further distortion of itsstrands will occur due to stress of the cable under load conditions.Engaging the cable and having outer grooved peripheries about which thecable is looped are a pair of rotatable pulleys 31 and 32. The pulley31, which is rotatably mounted on stationary brackets 44 fixed atop thetank 8, acts to guide the cable vertically downward in axial alignmentwith the lift rod 15. The pulley 32, which is rotatable on a shaft 33,is mounted for swinging movement upon a bell crank 34. This bell crank34 is pivotally mounted upon a stationary pin 35 which extends betweensuitable transversely-spaced brackets 37 mounted adjacent an edge of thetank 8.

The bell crank 34 has a long arm 38 upon which the pulley 32 is mountedand a short arm 39 which is coupled to the piston 27 by means of asuitable connecting rod 40. This connecting rod 40 is pivotallyconnected at one of its ends to the short bell crank arm 39 and at itsother end to the piston rod 41.

The anchoring means for the end X of the cable 30 preferably comprises apin 43 about which the end of the cable is looped in such a manner thatthe looped portion is free to rotate with respect to pin 43.

Assume now that the breaker is in open-circuit position, i. e., with theswitch member 13, the bell crank 34 and the piston 27 in theirrespective dotted line positions. If it is then desired to close thebreaker, the closing control valve 28 would be opened, thereby applyingpressurized fluid to the top of the piston 27 and driving it rapidlydownward toward its solid line closed-circuit position, This pistonmotion is transmitted through the connecting rod 40 to the bell crank 34and rapidly drives the bell crank and its associated pulley 32counterclockwise about their common pivot pin 3S. In so moving, thepulley 32 quickly lengthens the effective distance between pulleys 31and 32, and thereby pulls the driven end of cable 30 and theinterconnected switch member 13 rapidly upward toward the closed-circuitposition.

Because the bell crank has arms of unequal length, it will be clear thatthe horizontal displacement D of pulley 32 will be proportionatelygreater than the vertical stroke A of the driving piston 27.Furthermore, because the cable 30 is anchored at a fixed point and islooped over approximately 180 degrees of the periphery of pulley 32., itwill also be clear that the displacement of the cable 30 at the guidepulley 31 will be approximately double that of D. These two featuresproduce effective multiplication of the displacement of the piston 27and enable the switch member 13 to be moved through a relatively longstroke B in response to a relatively short stroke A of piston 27.

- Another feature of my bell crank 34 is that it is designed to providea progressively increasing mechanical fil 4 advantage as it is drivenfrom its dotted-line open position to its solid-line closed position.More specifically, during this movement, the effective lever arm whichextends normal to the cable 30 from the crank pivot axis at 35 becomesprogressively shorter, whereas the effective lever arm between the pivotaxis and the connecting rod 40 becomes progressively longer. Thisprogressively increasing mechanical advantage enables the liuid motor 20to more effectively overcome the progressively increasing retardingforces which are encountered as the switch member 13 is driven towardits closed-circuit position.

It will also be apparent that this cable-type of operating mechanism iscapable of moving the lift rod 15 through a straight line path withoutthe need for complex vstraight-line linkages, such as shown in theaforementioned Rankin patent. Obviating the need for such massive andcomplex linkages permits a substantial reduction in the overall mass ofthe operating mechanism. Still further reductions in mass are madepossible by virtue of the well-recognized fact that a multi-strandcable, such as my cable 30, has an appreciably greater strength-toweightratio than most solid rigid links, thus permitting the use of a cable ofcomparatively low mass. These reductions in rnass permit the parts ofthe mechanism to be more rapidly accelerated and thus permit appreciablereductions in the time required for tripping the breaker. A descriptionof a tripping operation will soon follow.

lt will also be apparent that, because the cable permits the omission ofa large number of the links and levers heretofore required forconventional operating mechanisms, the number of interconnecting jointsin the mechanism is correspondingly reduced. This minimizes the deectionor give characteristics of the mechanism, and thereby further decreasesthe tendency of the mechanism to retard initial acceleration. The giveof the cable itself is held to a minimum by the aforementionedpre-stressing operation.

To trip the breaker from the solid line closed-circuit position 4to thedotted line open circuit position, a tripping impulse would be appliedto the latch 29 thereby freeing the latch roller 2gb for upwardmovement. The spring 14 aided by springs 19, would then immediatelydrive the contact blade 13y downwardly toward its open circuit position.The cable 30, the bell crank 34, and the interconnected piston 27 would,of course, be pulled along behind the switch member 13, but because myinvention permits these parts to have a relatively low mass, they wouldotter little retardation to the desired rapid acceleration. Since thespace above the piston 27 would have been previously dumped toatmosphere by the thendeenergized control valve 28, at the end of theclosing stroke, the piston would be capable of moving upwardly asdescribed, substantially unimpeded by static fluid within the cylinder26.

For controlling the speed of this opening movement once the desiredinitial acceleration has been obtained,

there is provided an opening dashpot 45 which comprises a cylinder 46and a piston 47 coupled to the fluid motor piston 27. This dashpot 45 isconstructed in such a manner that it offers very little opposition toinitial acceleration. Only after this initial acceleration has beenachieved does it act to retard the then-opening parts. This retardationpermits etective circuit interrupting action and also acts to smoothlyterminate the opening stroke. Such speed control characteristics may beobtained in any well known manner, as by suitably grooving the internalwall of the dashpot cylinder 45. A suitable by-pass duct 48 containing acheck valve 49 permits substantiaily unimpeded movement of the piston 47in a downward or circuit-closing direction.

The location of the opening dashpot 45 at that eud of the cable 30 whichconstitutes the driven end during circuit-opening movement is anotherimportant feature of my invention. This location is referred tohereinafter as the motive-means end of the cable. By so locating thedashpot, I am able to miniinize any 'tendencyl of cable to whip orbecome alternately slack and tight during relatively abrupt changes inthe velocity -of the opening movement. This is the case because thedashpot 45, during opening movement, maintains the entire operatingmechanism including the cable 30 in tension and, as a result,effectively minimizes the tendency of any of the parts to overrun eachother.

The possibility that slack or whip will develop in the cable duringmovement in a reverse or circuit-closing direction is materiallylessened by the action of a metering pin 52, which I have incorporatedinto the fluid motor by xing it to the piston rod 41.V This metering pintits into an inlet oriiice 53 and is shaped to provide, in cooperh ationwith the oriiice, a gradually increasing ilow to the top side of piston27 during the first portion of closing stroke. Thus, the metering pinpermits the piston 27 and the operating mechanism to be brought up tospeed at a relatively gradual rate without any tendency toward abruptretardation. The opening .spring 14 further aids in reducing anytendency for the cable 30 to whip during closing movement. This is thecase because the spring 14 is located at the driven end of the cableduring closing movement and hence maintains the cable under tensionduring such movement.

My invention is especially applicable to multi-pole circuit breakerswherein a plurality of simultaneously operable switch members are to beoperated from a common source of motive power. For example, referring toFigs. 3 and 4, I have shown, in schematic form, a multi-pole breakercomprising three pole units 60, 61 and 62 each having a movable switchmember 13 corresponding to the similarly designated switch member 13 ofFig. l. All of these switch members 13 are to be simultaneously operatedfrom a common source of motive power, such as a fluid motor 20corresponding to the motor 2t) of Fig. 1. This motor is preferablymounted on the end pole unit 60. For providing the desired operation ofthe switch members, I provide three cables 30a, 3011, and 30C, each ofwhich has one of its ends stationarily anchored at 65 and its other endconnected to a different one of the lift rods of switch members 13. Aplurality of coaxially disposedl pulleys 32a, 32h, and 32e are mountedon a bell crank 34 corresponding to the similarly designatedsingle-pulley bell crank of Fig. l. Each pulley is arranged to engageone of the cables in the same manner as described in connection withFig. l. The three pulleys are mounted for movement in unison by suitablemeans such as a common centrally disposed shaft 66. The cable 30a, whichis looped about the grooved periphery of pulley 32a extends to pole unit6i) where it is looped about a guide pulley 31a which acts to guide itvertically downwardly into the pole unit, where it is connected to itscorresponding switch member 13. Similarly, the cable 36h, which islooped about the periphery of pulley 32h, extends to the center poleunit 61 where it is looped about guide pulley 31b which acts to guide itvertically downward into the pole unit 61, where it is connected to itscorresponding switch member 13. Similarly, the cable 30e, which islooped about periphery of pulley 32C extends to the remote end pole 62where it is looped about a guide pulley 31C which acts to guide thecable vertically downwardly into the pole unit 62, where it is connectedto its corresponding switch member 13. All of the guide pulleys 31a,31b, and 31e are rotatably mounted about a fixed axis in the same manneras described with respect to the guide pulley 31 ofthe single-polearrangement shown by Fig. l.

For assuring precise guidance of the two longer cables 36h and 39e Iprefer to provide idler pulleys which are arranged to engageintermediate portions of the cables 30b and 30C. For example, I provideon the pole unit 60 an idler pulley 67 which engages and guides cable30h. On pole units 60 and 61 I provide similar idler pulleys 68 and 69which engage and guide the cable 31C. All of these idler pulleys 67, 68,and 69 are suitably mounted for rotation about stationary axes.

Each of the cables 30a, 3011, and 30C is provided with a long-travelopening spring (not shown) adjacent a switch-member-connected end whichcorresponds to the opening spring 14 of Fig. l. Each of these springstends to maintain its corresponding cable in tension in the same manneras the long-travel spring 14 of Fig. l. Additionally, the iuid motor 20is provided with an opening dashpot 45 which corresponds to thesimilarly designed dashpot 4d of Fig. l. This dashpot 45 of Fig. 4 actsto maintain all of the cables under tension during circuit breakeropening movement, thereby suppressing cable whip action in the samemanner as the dashpot 45 in Fig. 1.

A feature which contributes to the ability of the cables to produceequal and simultaneous movement of the switch members is that thestationarily anchored ends of the cables are in alignment. For example,as shown in detail in Fig. 5, I have provided a common horizontallyextending stationary pivot pin 65 about which all three of the cablesAare looped and anchored.

Although I prefer to utilize three separate and distinct cables foroperating the three switch members, it will be apparent that certainfeatures of my invention readily lend themselves to other types of cablearrangements. For example, I may provide a single cable comprising atrunk terminating in three parallel branches, each of which is loopedabout one of the guide pulleys and is connected to a correspondingswitch member. The trunk portion of the cable would be looped about asingle grooved pulley mounted on the bell crank 34 and would have itsend stationarily anchored as at 65.

Although I have shown my invention applied to a multipole 'breaker ofthe type wherein simultaneous tripping and closing of all the poles isdesired, it will be apparent that certain features of my invention arealso applicable to multi-pole breakers wherein independent tripping ofthe individual pole units is desired. To this end, I would provideseparate bell-cranks and trip latches for each of the driving pulleys32a, 3217, and 32e. Closing devices for effecting the `desired closingoperation of such individ ually trippable parts are well-known.

Various other changes and modifications may be made without departingfrom my invention in its broader aspects. I, therefore, intend in theappended claims to cover all such changes and modifications as fallwithin the true spirit and scope of my invention.

I claim as my invention:

l. In an electric circuit breaker comprising a tank and a switch membervertically movable therein, motive means for effectingcircuit-controlling movement of said switch member, a guide pulleymounted atop said tank, a flexible cable-type tension memberstationarily anchored at one end and having a portion adjacent its otherend which is looped about said guide pulley and is connected to saidswitch member, a second pulley acting against said tension member andbodily movable to transmit circuit-controlling movement to said switchmember through said tension member, a pivotally mounted crank having along arm on which said second pulley is mounted and a short arm which iscoupled to and is actuable by said motive means to bodily move saidsecond pulley whereby to effect circuit-controlling movement of saidswitch member.

2. In an electric circuit breaker, a switch member, motive means foreffecting circuit-controlling movement thereof, a flexible cable-typetension member stationarily anchored at one end and connected at itsother end to said switch member, a rotatable pulley operatively engagingsaid tension member and bodily movable to transmit circuit-controllingmovement to said switch member through said tension member, a pivotallymounted crank having a long arm and a relatively short arm, means formounting said pulley on said long arm, and means coupling said motivemeans to said short arm and actuable by said motive means to bodily movesaid pulley whereby to effect circuit-controlling movement of saidswitch member.

3. In an electric circuit breaker, a switch member, motive means forelecting circuit-closing movement thereof, a exible cable-type tensionmember stationarily anchored at one end and connected at its other endto said switch member, a rotatable pulley acting against said tensionmember and bodily Amovable to transmit circuit-closing movement to saidswitch member through said tension member, a pivotally mounted crankhaving a long arm and a relatively short arm, means tor mounting saidpulley on said long arm, coupling means connected between said short armand said motive means for transmitting circuitclosing movement to saidcrank, the pivot axis of said crank being so located that the effectivelever arm between said pivot axis and said cable progressively decreasesduring circuit-closing movement and the eiective lever arm between saidaxis and said coupling means progressively increases during saidcircuit-closing movement.

4. In an electric circuit breaker, a switch member, motive means forelecting circuit-closing movement thereof, a flexible cable-type tensionmember stationarily anchored at one end and connected at its other endto said switch member, a rotatable pulley operativelyy engaging saidtension member and bodily movable to transmit circuitclosing movement tosaid switch member through said tension member, a pivotally mountedcrank having a long arm on which said pulley is mounted and a short armwhich is coupled to and is actuable by said motive means to bodily movesaid pulley thereby to edect circuit-closing movement of said switchmember, the pivot axis of said crank being so located that the crankprovides a progressively increasing mechanical advantage as said switchmember moves toward its closed position.

5. in an electric circuit breaker, a switch member, a flexiblecable-type tension member stationarily anchored at one end andoperatively connected at its other end to said switch member, springmeans at said other end biasing said switch member toward open-circuitposition, a pulley acting against said flexible member and bodilymovable to transmit circuit-closing movement to said switch memberthrough said flexible member, motive means coupled to said pulley andoperable to bodily move the pulley whereby to eiiect circuit-closingmovement of said switch member, and an opening dashpot coupled to saidflexible member at a location adjacent said one end, said dashpot actingto maintain said flexible member in tension during circuit-openingmovement.

6. In an electric circuit breaker, a biased-open switch member, a fluidmotor comprising a piston which is movable to effect circuit-closingmovement of said switch member, a liexible cable-type tension memberoperatively interconnecting said piston and said switch member fortransmitting forces therebetween, fluid control means for applying aprogressively increasing dow of lluid to said piston during initialcircuit-closing movement whereby to minimize abrupt variations inpiston-speed during circuitclosing movement, and means for mantainingsaid exible member in tension during circuit-opening movement comprisingan opening dash-pot coupled to said piston at the motor end of saidliexible member.

7. In a multi-pole electric circuit breaker, a switch member individualto each pole of the breaker, motive means for effecting simultaneouscircuit-controlling movement of said switch members, cable meansconnected to each of said switch members and having a portion which isstationarily anchored, pulley structure acting against said cable meansand bodily moveable to transmit circuitcontrolling movement to saidswitch members through said cable means, a pivotally-mounted crankhaving a long arm on which said pulley structure is mounted and arelatively short arm which is coupled to and is actuable 8 Y by saidmotive means to bodily move said pulley structure whereby to electcircuit-controlling movementof said switch members.

8. The combination of claim 7 in which the pivot axis of said crank isso located that the crank provides a progressively increasing mechanicaladvantage between said motive means and said switch members as themotive means moves the switch members in a circuit-closing direction.

9. in a meriti-pole electric circuit breaker, a switch member individualto each po-le of the breaker, common motive means for electingsimultaneous circuit-controlling movement of said switch members, aplurality of flexible cable-type tension members each of which isstationarily anchored at one end and is connected at its other end to adilerent one of said switch members, a plurality of pulley structureseach of which engagesV a different one of said tension members and isbodily movable to transmit circuit-controlling movement to itscorresponding switch member, support stmcture mounting said pulleystructures in coaxial relationship for bodily movement in unison andactuable to transmit circuitcontrolling movement to each of said switchmembers through its corresponding tension member, and means couplingsaid motive means to said support structure and operable by said motivemeans to actuate said support structure whereby to elect simultaneouscircuit-controlling movement of said switch members.

il). The structure of claim 9 in combination with means for maintainingsaid flexible members in tension during circuit-opening movementcomprising an opening dashpot coupled to said piston at themotive-means-end `of said flexible members.

11. In a multi-pole circuit breaker, a plurality of horizontally spacedpole units, a vertically movable switch member individual to each ofsaid units, common motive means mounted on one of said units andoperable to elect simultaneous circuit-controlling movement of saidswitch members, a plurality of guide pulleys each of which is mounted ona dilerent one of said pole units, a plurality of flexible cable-typetension members each having an end portion which is looped about one ofsaid guide pulleys and extends downwardly into coupled relationship withone of said switch members, means for stationarily anchoring theopposite end of each of said tension members, a plurality of rotatablepulley structures each of which operatively engages a dilierent one ofsaid tension members and is bodily movable to transmitcircuit-controlling movement to its corresponding switch member, supportstructure mounting said pulley structures in coaxial relationship forbodily movement in unison and actuable to transmit circuit-controllingmovement to each of said switch members through its correspondingtension member, and means coupling said motive means to said supportstructure and operable by said motive means to actuate said supportstructure whereby to eli'ect simultaneous circuit-controlling movementof said switch members.

l2. The combination of claim l1 in which said opposite ends of saidtension members are anchored in horizontally aligned relationship.

13. ln a multi-pole circuit breaker, a switch member individual to eachpole of the breaker, common motive means for eecting simultaneouscircuit-controlling movement of said switch members, a plurality offlexible cabletype tension members each of which is stationarilyanchored at one end and is connected at its other end to a different oneof said switch members, a plurality of rotatable pulley structures eachof which operatively engages a different one of said tension members andis bodily moveable to transmit circuit-controlling movement to itscorresponding switch member, a pivotally mounted bell crank having along arm and a short arm, means for mounting said pulley structures incoaxially disposed relationship on said long arm, and means couplingsaid short arm to said motive means and actuable by said motive means tobodily move said pulley structures in unison whereby to effectsimultaneous circuit-controlling movement of said switch members.

14. In a multi-pole circuit breaker, a plurality of horizontally spacedpole units, a switch member individual to each of said pole units,common motive means mount ed on one of said pole units and operable toeffect simultaneous circuit-controlling movement of said switch members,a plurality of eXible tension members each of which is stationarilyanchored at one end on said one pole unit and is connected at its otherend to a different one of said switch members, a plurality of rotatablepulley structures each of which operatively engages a different one ofsaid tension members and is bodily movable to transmit circuitcontrolling movement to its corresponding switch member, supportstructure mounting said pulley structures in coaxial relationship forbodily movement in unison and actuable to transmit circuit controllingmovement to each of said switch members through its correspondingtension member, and means coupling said motive means to said supportstructure and operable by said motive means to actuate said supportstructure whereby to effect simultaneous circuit controlling movement ofsaid switch members.

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